Viability of Streptococcus mutans toothbrush bristles.

Abstract

PURPOSE: Employing microbial culture, the purpose of this study was to assess in vitro the viability of Streptococcus mutans on toothbrush bristles relative to the drying time. METHODS: Forty-five toothbrushes were soaked in a suspension containing S. mutans (ATCC 25175) in a 1,720.000 cfu/mL concentration (0.5 McFarland scale) for 4 minutes, rinsed in sterile tap water, and assigned to 9 groups. Group 1 toothbrushes were immediately incubated in CaSaB CaSaB (bacitracin sucrose broth-selective enrichment broth) culture medium for 4 days. Toothbrushes from groups 2 to 9 were kept at room temperature for 4, 8, 12, 24, 36, 48, 60, and 72 hours, respectively, and subsequently incubated in CaSaB culture medium. RESULTS: It was observed that micro-organisms were present on toothbrushes of groups 1 to 3, ranging from 50 to 100+ cfu. From the 12-hour drying period on, there was no growth of S. mutans. Regarding the S. mutans cfu, the results were expressed in scores and submitted to the Kruskal Wallis statistical test. It was observed that groups 1 to 3 were similar to each other (P>.05) and differed significantly (P<.001) from other groups, which, in turn, behaved similarly (P>0.05). From the 12-hour drying period on, there was a statistically significant decrease in the number of S. mutans cfu (P<.01). CONCLUSION: It may be concluded that Streptococcus mutans remained viable on the toothbrushes' bristles for up to 8 hours.